In mass and/or rapid transit operations, it is common practice to employ an electromagnetic speed sensing device or signal generator to measure the velocity of the axles and/or wheels of the vehicles of a railway train. Generally, these previous electromagnetic speed generators included a tooth rotor or gear member coupled to the axles of the railway vehicle which moves past an electromagnetic stator or pickup member to produce signals which are directly proportional to the velocity or speed of the wheels of the railway vehicle. It will be appreciated that, while these speed sensing devices have operated satisfactorily to varying degrees, there are certain aspects which must be carefully considered and effectively dealt with in order to maximize the velocity measuring operation. An acceptable speed measuring device must be capable of withstanding extreme shock and vibrations which are ever present in a railway vehicular milieu. The violent and irregular agitation has a detrimental effect on any speed signal generator which utilizes frangible or unstable elements. Such previous apparatus is susceptible to breakage and misalignment of parts which either totally destroys or markedly reduces the signal generating ability of the speed sensing device. It has been found, from long-term wheel protection testing, that certain malfunctions in the speed sensors could erroneously simulate a wheel slip condition. For example, during testing, a foreign object or a piece of debris struck one of the gear teeth of the rotor. This resulted in the loss of a piece of one of the teeth of the gear. This caused a cycling of the brake cylinder pressure due to the lost tooth falsely appearing as a wheel slip. Thus, it was determined that the detection and management of this type of a malfunctional condition was required to be handled by the logic. The necessary logic to detect this situation was to be dealt with by the software. If this condition is sensed and detected, the axle signals from the affected axle will be substituted with the signals from the other axles on the truck. In practice, the impact of a broken gear or any other malfunction which exhibits similar symptoms can cause the brakes to pulse rapidly between release and application with a tendency to cause the brakes to be biased toward the released position. At low vehicular speeds, where the problem is the most pronounced, the net pressure of the brake cylinder can be reduced to zero on the affected truck. Further, if the train continues to run in actual service for as little as a half a day, the wheel slip control valve on the affected truck will undergo millions of brake release and application cycles which results in undue wear and can result in failure of the equipment.